CRAWFORD AND VERNON COUNTIES - Twenty-five Tainter Creek Watershed Council members and interested citizens gathered at the Hornby Hollow farm of Brad Robson on Saturday, Sept. 19. The field day participants heard presentations about innovative planting experiments, financial impacts of soil loss in different tillage, cash crop and cover crop systems, and discussed the benefits of different cover crop strategies for soil health.

Before the presentations started, participants were treated to a lunch of grilled burgers from beef raised by the Robsons, grilled brats from the Klinkner Kountry Store, and cheese curds from Westby Cooperative Creamery.

“I would say that I had mixed results this growing season,” Robson said. “It all seemed to be going very well until we went over a month with no rain – that set things back. Nevertheless, I was pleasantly surprised when I got the numbers back and I’m happy that I did the experiment.”

In Robson’s top fieldhe planted corn on May 10 in 30 and 60-inch rows. At the same time he planted a Prairie Creek Seeds ‘Interseeder Plus’ cover crop mix. The mix includes annual ryegrass, crimson clover, balansa clover, and a hybrid brassica (a cross between a forage turnip and a forage rape). He used eight pounds per acre between the 30-inch rows, and 14 pounds per acre between the 60-inch rows. 

No herbicide was applied, but on April 17 he used, per acre, 80 pounds of MAP (monoammonium phosphate - phosphorous and nitrogen); 80 pounds of SOP (sulfate of potash); 40 pounds of Urea; and 40 pounds of AMS (ammonium sulfate). On June 8, he used 150 pounds of Urea and 100 pounds of AMS. In total, he applied 140 pounds of nitrogen.

The field had been no-tilled for 15 years with a corn and bean rotation – beans in 2019. Robson had already harvested the corn for silage.

“I believe I lost some corn yield due to weed pressure, and a shortage of moisture and nutrients,” Robson said. “I assumed four ton per acre (as fed) in corn silage loss.”

The cover crop cost him a total of $170 for 8.25 acres ($20.60/acre). He did not factor in the cost or return on corn silage. The forage yield has 12.26 percent protein, 150.18 RFV (relative feed value – a comparison of the quality of forages relative to the feed value of full bloom alfalfa), and 22.62 percent dry matter.

In his middle field Robson had planted oats on April 1 (two bushels/acre); and on August 4, he planted a forage max cover crop mix (oats, barley, lentils, peas, turnip, and forage brassica) at 50 pounds per acre, and five pounds per acre of Teff (a warm season cereal crop). He combined the oats on July 29, and got 60 bushels per acre, and 1.2 tons of straw.

On April 17, per acre, he used 80 pounds of MAP and SOP, and 40 pounds of Urea and AMS.  On August 4 he used, per acre, 75 pounds Urea and 50 pounds AMS.

The field had been harvested for corn silage in 2019, and had been in long time hay production before that. He received no rain between June 26 and August 27 – the field received half an inch of rain on August 28.

The cover crop cost was $76.40 or $34.73/acre for 2.2 acres. The nutrient analysis for the Forage Max, oat and Teff mix was 20.49 percent protein, RFV 190.94, and dry matter 14.75 percent.

His bottom fieldwas planted into sorghum/sudan grass, and harvested for silage bales, with the third crop available for late season grazing. On June 4, he planted 10 pounds per acre of sorghum/Sudan grass and five pounds per acre of Italian ryegrass. On August 15, he applied 100 pounds of Urea, and 50 pounds AMS, per acre.

On July 1, he harvested two silage bales; and on August 12, he harvested 4.5 silage bales.

The field has been no-till for 15 years. In 2018 it was planted in soybeans, and in the fall of 2018 it was planted in rye. In the spring of 2019, Robson frost seeded red clover (five pounds/acre) and alfalfa (seven-to-eight pounds per acre). 

On June 8, he took off two bales/acre of rye baleage. On June 11, he planted sorghum/Sudan at 22 pounds per acre. On July 13, the sorghum/Sudan yielded two bales per acre (rye regrowth and early Sudan). On August 24, the sorghum/Sudan yielded nine bales per acre. It will be grazed at about the end of October, with about two bales of regrowth.

There was no early fertilizer applied to this field. Robson made an effort to reduce the cost of seed through lowering the seeding rate of sorghum/Sudan. The cover crop cost $1/per acre for 3.25 acres - $32.50, plus $22.75 for the Italian ryegrass, for a total cost of $55.25, or $17 per acre.

The sorghum/Sudan and Italian ryegrass had a nutritional value of protein 19.82 percent, RFV 148.48, and dry matter 16.44 percent.

Value of lost soil

Ryan Woodill, who farms at Woodhill Farms, gave a rundown of the value of the soil loss per acre under different systems of tillage, cropping, and cover crops, on five fields on the farm.

The first field was spring chisel disked and planted for corn silage. The annual soil loss was 20.50 tons/acre/year, for a soil loss valued at $246,86 per acre.

The second field was spring vertical tilled and planted for corn silage. The annual soil loss was 16.70 tons/acre/year, for a soil loss valued at $201.13 per acre.

The third field was spring vertical tilled, with a cover crop, and then planted for corn silage to a small grain cover crop. The annual soil loss was 6.99 tons/acre/year, for a soil loss valued at $84.11 per acre.

The fourth field was a no-till, planted for corn silage to a small grain cover crop. The annual soil loss was 2.68 tons/acre/year, with a soil loss valued at $32.24 per acre.

The fifth field was no-till, planted into corn silage with an aerial seeded rye cover crop. The annual soil loss was 0.14 tons/acre/year, with a soil loss valued at $1.66 per acre.

Woodill also discussed the situation producers in Iowa are currently facing with corn damaged by the recent derecho.

For producers whose corn was damaged, but who were able to harvest some, followed by tilling the rest in using a moldboard plow, the annual soil loss will be 24.6 tons/acre/year, with a total soil loss valued at $296.18 per acre.

Prairie Creek Seeds

Carl Delafield of Prairie Creek Seeds made a presentation to the group about his company’s cover crop seeds. He also led the group in an inspection of soil pits that had been dug in each of the three fields where Robson conducted his experiments.

“I’ve been in the seed business for 35 years,” Delafield said. “Twenty years of that has been focused on cover crops and grass management.”

Delafield told participants that he is not totally against use of tillage.

“The key is that you have to use tillage intentionally, and not recreationally,” Delafield said. “When you do till, you want to till as shallowly as possible, and plant your covers using no-till.”

Delafield discussed three types of forage brassicas used in fields – radish, turnip and the tankard turnip.

“Some people worry about grazing turnips because a cow could choke on the bulb,” he explained. “For those folks, we offer the tankard turnip which has a much smaller bulb.”

Delafield said that he had also heard of people that were so worried about the forage radishes that they were actually attempting to till them in.

“The forage radish is made up almost all of water,” he said. “The radish bulb will disintegrate by spring, and offer a high protein/nitrogen kickoff, as well as sending down long tap roots which allow spaces for other roots and worms to move through the soil profile.”

In the soil pits, Delafield showed participants that the amount of loose topsoil was much greater on the field lowest down the hill, and much less for the soil at the top of the hill. In all cases, though, he was able to demonstrate that the cover crop roots had penetrated the soil profile down to the bottom of the pit, and there were also worm tunnels at depth in the pit.